RSpec 3 and why I `expect(you).to care`

Red Dot Ruby Conf 2014 talk about the decisions taken to create RSpec 3

Transcript

1. RSPEC 3 AND WHY I
   expect(you).to care
   

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2. BEFORE(:TALK)
   

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6. RSPEC 3 AND WHY I
   expect(you).to care
   

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7. SEMANTIC VERSIONING
   

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8. HISTORY
   

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9. RSPEC 0.x
   

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10. RSPEC 1.x
    

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11. RSPEC 2.x
    

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12. RSPEC 3.x
    

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13. I EXPECT(YOU).TO CARE
    

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14. WHY YOU.SHOULD CARE
    

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15. class MyCustomObject
    def fuzzy?
    true
    end
    end
    !
    describe do
    specify do
    my_model = MyCustomObject.new
    expect(my_model).to be_fuzzy
    end
    end
    

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16. class MyCustomObject
    def fuzzy?
    true
    end
    end
    !
    describe do
    specify do
    my_model = MyCustomObject.new
    my_model.should be_fuzzy
    end
    end
    

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17. class MyCustomObject
    def fuzzy?
    true
    end
    end
    !
    describe do
    specify do
    my_model = MyCustomObject.new
    expect(my_model).to be_fuzzy
    end
    end
    

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18. describe do
    specify do
    expect { fail }.to raise_error
    !
    x = 1
    expect { x += 1 }.to(
    change { x }.from(1).to(2)
    )
    end
    end
    

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19. EXPECT(YOU).TO CARE
    

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20. obj.should matcher
    

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21. expect(obj).to matcher
    

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22. obj.should_receive
    

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23. expect(obj).to receive
    

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24. obj.stub(:msg)
    

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25. allow(obj).to receive
    

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26. obj.should_receive(
    some: [vals]
    )
    

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27. expect(obj).to(
    receive_messages(some: [vals])
    )
    

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28. DEPRECATED?
    

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31. DEPRECATED?
    

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32. MONKEY PATCHING
    

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33. obj.should matcher
    

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34. class FuzzyProxy < BasicObject
    def initialize(target)
    @target = target
    end
    !
    def fuzzy?
    true
    end
    !
    def method_missing(*args, &block)
    @target.__send__(*args, &block)
    end
    end
    

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35. describe FuzzyProxy do
    !
    it 'is fuzzy' do
    instance = FuzzyProxy.new(:some_object)
    instance.should be_fuzzy
    end
    !
    end
    

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37. REMOVING
    MONKEY PATCHING
    

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39. NO MONKEY PATCHING
    BY DEFAULT
    

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40. describe "SomeClass" do
    !
    context "in some situation" do
    !
    it "will do something" do
    # ...
    end
    !
    end
    !
    end
    

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41. RSpec.describe "SomeClass" do
    !
    context "in some situation" do
    !
    it "will do something" do
    # ...
    end
    !
    end
    !
    end
    

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42. RSpec.configure do |config|
    
    !
    config.disable_monkey_patching!
    
    !
    end
    
    

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43. FORMATTERS
    

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46. MODULARISATION
    

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47. class CustomFormatter
    # This registers the notifications this formatter
    # supports, and tells
    RSpec::Core::Formatters.register self, :example_sta
    !
    def initialize(output)
    @output = output
    end
    !
    def example_started(notification)
    @output << "example: “
    @output << notification.example.description
    end
    !
    end
    

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48. PHILOSOPHY
    

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49. its(:thing) { … }
    

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50. it { should be … }
    

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51. it { is_expected.to be … }
    

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52. its(:thing) { … }
    

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53. require ‘rspec/its'
    !
    describe do
    !
    person = Struct.new(:first, :last) do
    def name
    [first, last].join(' ')
    end
    end
    !
    subject(:bob) { person.new('Bob', 'Jones') }
    !
    its(:name) { is_expected.to eq 'Bob Jones' }
    !
    end
    

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54. examples$ rspec lies_spec.rb --format doc
    !
    !
    name
    should eq "Bob Jones"
    !
    Finished in 0.00094 seconds (files took 0.09512
    1 example, 0 failures
    examples$
    

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55. require ‘rspec/its'
    !
    describe "#name" do
    !
    person = Struct.new(:first, :last) do
    def name
    [first, last].join(' ')
    end
    end
    !
    it "combines first and last" do
    bob = person.new('Bob', 'Jones')
    expect(bob.name).to eq 'Bob Jones'
    end
    !
    end
    

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56. examples$ rspec refactor_spec.rb --format doc
    !
    !
    name
    combines first and last
    !
    Finished in 0.00084 seconds (files took 0.0084
    1 example, 0 failures
    examples$
    

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57. VERIFIED DOUBLES
    

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58. describe "verified doubles" do
    !
    it "does something" do
    my_obj = instance_double(
    "MyObject", does: "cool things”
    )
    expect(my_obj.does).to eq "cool things"
    end
    !
    end
    

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59. describe "verified doubles" do
    !
    class MyObject
    end
    !
    it "does something" do
    my_obj = instance_double(
    "MyObject", does: "cool things”
    )
    expect(my_obj.does).to eq "cool things"
    end
    end
    

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60. examples$ rspec verified_doubles_in_situ_spe
    F
    !
    Failures:
    !
    1) verified doubles does something
    Failure/Error: my_obj = instance_double("M
    MyObject does not implement: does
    # ./verified_doubles_in_situ_spec.rb:7:in
    !
    Finished in 0.00046 seconds (files took 0.07
    1 example, 1 failure
    

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61. describe "verified doubles" do
    !
    class MyObject
    def does; true; end
    end
    !
    it "does something" do
    my_obj = instance_double(
    "MyObject", does: "cool things”
    )
    expect(my_obj.does).to eq "cool things"
    end
    end
    

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62. describe "verified doubles" do
    !
    class MyObject
    def does; true; end
    end
    !
    it "does something" do
    my_obj = MyObject.new
    allow(my_obj).to receive(:other) { "things" }
    expect(my_obj.other).to eq "things"
    end
    end
    

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63. examples$ rspec verify_partial_doubles_spec.
    .
    !
    Finished in 0.01582 seconds (files took 0.12
    1 example, 0 failures
    

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64. describe "verified doubles" do
    !
    class MyObject
    def does; true; end
    end
    !
    RSpec.configuration.mock_with :rspec do |mocks|
    mocks.verify_partial_doubles = true
    end
    !
    it "does something" do
    my_obj = MyObject.new
    allow(my_obj).to receive(:other) { "things" }
    expect(my_obj.other).to eq "things"
    end
    end
    

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65. examples$ rspec verify_partial_doubles_spec.
    F
    !
    Failures:
    !
    1) verified doubles does something
    Failure/Error: allow(my_obj).to receive(:o
    # does not
    implement: other
    # ./verify_partial_doubles_spec.rb:13:in
    !
    Finished in 0.00562 seconds (files took 0.08
    1 example, 1 failure
    

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66. CLEAN HOUSE
    

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67. object.stub!
    

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68. it { stub “something” }
    

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69. it { mock “something” }
    

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70. at_least(0).times
    

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71. not_to
    raise_error(Specific)
    

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72. autotest support
    

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73. textmate formatter
    

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74. describe do
    let(:thing) { "happen" }
    !
    before(:all) do
    thing
    end
    !
    it { }
    end
    

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75. examples$ rspec broken_let_spec.rb
    F
    !
    Failures:
    !
    1)
    Failure/Error: thing
    RuntimeError:
    let declaration `thing` accessed in a
    `before(:context)` hook at: examples/brok
    `let` and `subject` declarations are not
    intended to be called in a `before(:conte
    hook, as they exist to define state that
    is reset between each example, while
    

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76. describe do
    let(:thing) { "happen" }
    !
    before(:all) do
    thing
    end
    !
    it { }
    end
    

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77. describe do
    !
    before(:all) do
    allow(Object).to receive(:message)
    end
    !
    it { Object.message }
    end
    

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78. examples$ rspec before_all_stubs_broken_spec
    F
    !
    Failures:
    !
    1)
    Failure/Error: allow(Object).to receive
    The use of doubles or partial doubles
    from rspec-mocks outside of the per-test
    lifecycle is not supported.
    # ./before_all_stubs_broken_spec.rb:4:in
    !
    Finished in 0.00504 seconds (files took 0.07
    1 example, 1 failure
    

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79. describe do
    !
    before(:all) do
    RSpec::Mocks.with_temporary_scope do
    allow(Object).to receive(:message)
    end
    end
    !
    it { # Object.message }
    end
    

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80. UPGRADING
    

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81. TRANSPEC
    

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82. describe do
    !
    subject(:string) { "a string" }
    !
    it { should be_a String }
    its(:length) { should == 8 }
    !
    specify do
    string.should == "a string"
    end
    !
    end
    

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83. examples$ transpec
    Gathering the spec suite data...
    !
    Converting examples/upgrade_spec.rb
    !
    Summary:
    !
    2 conversions
    from: it { should ... }
    to: it { is_expected.to ... }
    1 conversion
    from: obj.should
    to: expect(obj).to
    !
    6 conversions, 0 incompletes, 0 warnings, 0
    

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84. describe do
    !
    subject(:string) { "a string" }
    !
    it { is_expected.to be_a String }
    !
    describe '#length' do
    subject { super().length }
    it { is_expected.to eq(8) }
    end
    !
    specify do
    expect(string).to eq("a string")
    end
    !
    end
    

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85. AFTER(:TALK)
    

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86. THANKS
    

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88. THANKS
    @JONROWE
    HTTP://JONROWE.CO.UK
    

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